PharmChem Inc. has developed a new sweat patch product, the FastPatch TM, which reduces minimum wear times to detect cocaine and most other drugs of abuse from the full day typically required with standard sweat patches (Liberty et al., 1999a) to 20 or 30 minutes through mild heating (Liberty, 2003). Additionally, there is an increasing need and growing market for the detection of crack use distinct from other cocaine. Recent research (Martin et al., 1989) has identified unique pyrolytic metabolites of crack, anhydroecgo-nine methylester (AEME) and ecgonidine (ECD) through GC/MS. It is likely that a low-cost EIA procedure for detection of crack use will be available within a year, increasing the market potential for detection using a Fastpatch (tm). During Phase I, 180 subjects wore two FastPatch prototypes (one on each hand) and only one patch per subject was needed to obtain sufficient sweat eluate for GC/MS. This finding has positive market potential. Cocaine use was detected in sweat of 92.4 percent of subjects, comparable to 91 percent with EMIT urinalysis in a high prevalence sample. Crack metabolites were successfully detected in 54 percent of subjects. While there were no significant differences in detection rates between 15, 20, and 30 min. wear periods, all wear periods successfully detected substantial cocaine/crack use, and a shorter 10 min. condition will be tested. This finding has positive market potential. During Phase II, these changes will occur: Fast patches will be worn in moderate and low prevalence samples, a shorter wear period will be added, more biological tests will be included (e.g., standard sweat patches and GC/MS of urine), testing for more drugs (heroin and marijuana), data collection will expand to include both a residential drug treatment program and a workplace, low-prevalence sample, the latter a venue with positive market potential. The FastPatch avoids problems with urinalysis such as violations of privacy, dilution or substitution of specimens, possibility of disease transmission, and transport of noxious fluids. Advantages over the standard sweat patch include a longer window of detection (2-3 wks. versus 2-3 days) and a shorter minimum period of wear needed to detect most drugs (10-20 m n. versus 24 hrs.).